The Southwestern Virginia Field Office of Virginia Ecological Services is located in Abingdon, Virginia. The office is strategically located in the heart of the Upper Tennessee River Basin. Encompassing about 21,390 square miles, including the entire drainage of the Tennessee River and its tributaries upstream of Chickamauga Dam in Chattanooga, Tennessee, the Upper Tennessee River Basin is home to a diversity of fish and mussels that is unsurpassed in North America. The major tributaries of the Upper Tennessee River Basin include the Clinch (4,413 square miles), Holston (3,776 square miles), French Broad (5,124 square miles), Little Tennessee (2,627 square miles), and Hiwassee (2,700 square miles) rivers. The office cooperates with partners throughout the eastern U.S. to protect and recover aquatic threatened and endangered species and associated habitat within the Upper Tennessee River Basin.